1. PHIL105: The Big Questions
Trimester

2. What is Philosophy?
Using reason & rational argument to answer the big questions
The big questions are:
The very important ones
Hard to answer even when we have all or most of the relevant facts

3. Topics Dan Week 1: Personal identity Week 2: The good life
Week 3: The meaning of life
Dan

4. Introduction to Personal Identity
PHIL105 – T3, 2011 Lecture 1

5. Personal Identity Who am I?
What makes me the same person through time?
What happens to me if I’m copied?
What about people who have their brains chopped in half!?!
Hard questions, even if we have all of the facts

6. Terminology Numerical identity Qualitative identity
A (literally) unique thing
Qualitative identity
Looks, feels, tastes (etc) identical
Essential properties
Required for numerical identity
Accidental properties
Can change without affecting numerical identity

7. Personal Identity & the Afterlife
It can comfort us to think that our loved ones live on somehow after death
But what would that really entail?

8. Reincarnation You are reborn into a new body after death
PROBLEM: Reincarnations don’t seem to be the same person

9. Resurrection You (and your body) come back to life after you die
PROBLEMS:
Need an earth-like place to go to
If we’re recreated exactly the same, we’ll just die again
Some of your atoms will be part of other organisms

10. Soul Liberation When we die, our soul
leaves our body to live on somewhere else
PROBLEMS:
What, exactly, is a soul?
What would your soul be like?
Is a soul just the hard drive that our memories, beliefs, and personality are written on to?
Is your soul without your body really you?

11. Cryogenics Being frozen until medical advances can fix all your
ailments
PROBLEMS:
Technological risk
The brain may be too damaged
Ice-cream headache

12. Cyborgs Use technology to keep us alive! PROBLEMS: Will it ever work?
How will we know?

13. Personal Identity & the Accident Victim
Brain damage and amnesia could drastically change what a person is like
But, would it change who they are?

14. COMINS Continuity of the Mental Is Necessary for Survival
VERDICT: Mr Edward’s son has not survived the accident
PROBLEM:
How much and what type of ‘the mental’ has to continue and how must it continue?

15. CEBINS Continued Existence of the Body Is Necessary for Survival
VERDICT: Mr Edward’s son has survived the accident
PROBLEM:
This may be necessary, but is it sufficient for a person to survive?

16. CESINS Continued Existence of the Soul Is Necessary for Survival
VERDICT: Mr Edward’s son has survived the accident
PROBLEM:
If it’s not the body or the mental… what, exactly, is the soul again?

17. Summary – What Makes Us Survive?
Continuation of mental
Continuation of body
Continuation of soul
A combination
Has Martha’s Mum survived?
Has Edwards’ son survived?
Maybe we don’t survive?

18. Philosophy Clinic: How to Argue that a Theory is the Best Theory
Explain the main theories and their main strength
Apply the theories to real and whacky examples
A good theory will give an answer in each case (who is the same person?)
The best theory will give the right answer for a good reason in most of the cases
Good reasons for right answers are generally consistent with our reflected-upon intuitions
But you can also explain why some particular intuitions are wrong (and your theory is right)

19. The elusive ‘I’ Who here thinks they exist? Cogito ergo sum
Meditation time!! ??
Lets ‘find ourselves’
Where am ‘I’ ?!?!

20. For Next Time
Read:
Law, Stephen: Brain Transplants, ‘Teleportation’ and the Puzzle of Personal Identity
Parfit, Derek: Divided Minds and the Nature of Persons

21. More on Personal Identity
PHIL105 – T3, 2011 Lecture 2

22. Personal Identity
We want our theory to provide answers to questions like these:
What makes me me?
What makes me the same person through time?

23. Terminology Numerical identity Qualitative identity
A (literally) unique thing
Qualitative identity
Looks, feels, tastes (etc) identical
Essential properties
Required for numerical identity
Accidental properties
Can change without affecting numerical identity

24. Sci-Fi Disclaimer
The following ‘whacky’ thought experiments may never be possible in real life
But, then again, they might!
Regardless, a good theory of personal identity should be able to answer theoretically possible as well as actually possible problem cases

25. Animal Theory In essence, each person is a living animal
What essentially makes me me through time is that I am the very same living creature as the one in the photos

26. Brain Transplant Case
A brother and sister have their brains swapped while they sleep one night
Problem for the Animal Theory

27. Brain Theory In essence, each person is their unique living brain
What essentially makes me me through time is that I have the very same brain as the ‘me’s in the photos

28. Brain Recorder Case
This device re-splices the existing brain bits so that a pre-recorded personality (etc) can be downloaded into the (same) old brain
Problem for the Brain Theory

29. Stream Theory AKA: Psychological Continuity Theory
In essence, each person is (the right kind of) continuation of psychological properties
E.g. What MIGHT essentially makes me me through time is that my memories are psychologically continuous

30. The Reduplication Case
This device makes perfect copies of anything put in cubicle A (in c. B) but the original is vaporized
A new model also makes a duplicate in cubicle C
Problem for the Stream Theory?

31. Modified Stream Theory
In essence, each person is (the right kind of) continuation of psychological properties
Except when two or more people are psychologically continuous (in the right kind of way) from one person
In which case, none of those later people are the same person as the original person

32. The Duplicator Gun Case
This device makes a perfect copy of anything shot with it but it doesn’t destroy the primary target
Problem for the Modified Stream Theory

33. They All Seem Wrong! The Animal Theory The Brain theory
Gets the brain transplant and recorder cases wrong
The Brain theory
Gets the brain recorder case wrong
The Stream Theory (AKA the Psychological Continuity Theory)
Gets the reduplication and duplicator gun cases wrong
The Modified Stream Theory
Gets the duplicator gun cases wrong

34. The Teletransporter Case
You have been ‘teletransporting’ to work (on a very distant planet) for 3 years
You are at work when you are informed that the ‘teletransporter’ really works like the reduplicator (it copies & kills you)
Do you get in and ‘teletransport’ home? Why? Why not?

35. Divided Minds and the Nature of Persons
Derek Parfit
Split-brain cases tell us something interesting about personal identity
There are no ‘persons’ in a split-brain case
But there were no ‘persons’ before the brain was split either

36. Why Chop Your Brain in Half?
Suffers of severe epilepsy had their corpus callosum chopped in half to prevent seizures spreading across hemispheres
This means that the two halfs of the brain cannot communicate directly with each other
The resulting body acts as normal in most cases and suffers from less debilitating seizures

37. The Experiments
Left hemisphere controls right eye & hand (& speech in right-handers)
Using a special technique, each hemisphere was exposed to a different stimuli
Each hand responded as though there is a separate stream of consciousness in each hemisphere

38. How Visual Fields Really Work

39. More Info on the Actual Split-Brain Experiments
A picture is flashed in the left visual field (for a right-hander) so fast that the right eye can’t see it, but the left eye can.
When asked, the person says they couldn’t see the picture
But the ‘locked-in’ right hemisphere did see it!

40. What ‘Goes With’ What?
When asked to point to the picture that ‘goes with’ what they see…
Each hand goes for a different picture!

41. Does Each Hemisphere Know about the Other One?
They seem to ignore or be unaware of each other
Before the op. patients can name objects on both sides, but only on one side after the op.
Interestingly, they don’t complain about the loss

42. The Ego Theory
What essentially makes me me through time is that all of the ‘me’s are the same subject of experiences (ego)
What unites the many experiences I have had in my life is that I was the one having them all
The Cartesian View is an example of this (my ego is my soul)

43. The Bundle Theory
We cannot explain our survival through time by referring to a ‘person’
Because no ‘person’ (subject of our experiences) exists!
There are just bundles of mental states (experiences) tied together by the causal relation of memory (experiencing remembering previous experiences)
We call these bundles ‘lives’

44. The No Self View Buddha was the first bundle theorist
His No Self View is a type of bundle theory
People have ‘nominal existence’ (we sometimes talk as if they exist), but only the parts that make them up really exist

45. Parfit: What We Believe Ourselves to Be
Science tells us that:
There is no evidence for the Ego Theory
There is evidence for the Bundle Theory
Most of us believe something like the Ego Theory to be true
Unfortunately, most of us hold false beliefs about who we are!
Me: But does science tell us that?

46. Replacing Your Cells Case
A high-tech alien is going to replace some of your cells with identical replicas (all at once)
If it changes 1% of your cells, are you the same person?
What if it changes 100% of your cells?
There are answers to these qns

47. How We are Not What We Believe
How could we even know if 49% or 50% (or whatever) replaced cells is the right place for the line?
It is implausible that a few cells will make the difference in the Replacing Your Cells Case
But that is what our natural beliefs/intuitions force us to say!
Therefore, we should embrace the Bundle Theory

48. Bundle Theory Applied
When applied to all of the cases, the Bundle theory rejects the question, ‘what happens to you?’
The Bundle Theory can explain what happens, but it doesn't refer to persons (because they don’t really exist)
If ‘50% of your cells are replaced,’ then 50% of that bodies cells are replaced
You don’t end or survive because you were never there in the first place!
These cases only raise worries because we don’t properly understand the nature of persons

49. PARFIT: Split-Brain Cases and the Ego Theory
The Ego Theory says that all of the experiences in the split-brain case are being had by the one ego/person (but in 2 streams)
The Ego Theory is wrong because it ignores the disunity between the two streams of consciousness
The ego can’t just split in two
Because it is supposed to be the one unique persisting essential element of a person

50. PARFIT: Split-Brain Cases and the Bundle Theory
On the Bundle Theory, bodies normally have an awareness of having several different experiences at any one time
There is no ‘I’ (an independently existing & persisting thing) required for the explanation
In the split-brain case, there are two separate states of awareness of experiences
But neither of those states is a unique, independently existing & persisting ‘I’ (they don’t exist)

51. Parfit: Split-Brain Cases 1
While both the Ego Theory and the Bundle Theory can explain our normal awareness of experiences…
Only the Bundle Theory provides a good explanation for the split-brain cases
Combined with the lack of scientific evidence for the Ego Theory, we should accept the Bundle Theory
Which means that our belief in our persisting ego/self/I is false!

52. Parfit: Split-Brain Cases 2
When someone’s brain is divided, two streams of consciousness are created
Neither of the streams is the same person as the original
But, this is just like ordinary survival!
We are just bundles of mental states tied together by remembering what the previous experiences were like
So, with every new experience, who we are changes (our old numerical identity dies!)

53. For Next Time Get ready to discuss: Read: The Good Life
Singer, Peter (ed.) (1994). Excerpts of Ultimate Good, in Ethics, pp , , Oxford University Press. (Read all except Nozick, pp )